Consider the following page reference string for a 10-page executable. 0,1,1,3,4,5,2,2,6,6,7,8,7,9,9,6,5,9 How many page faults would occur for the following replacement algorithms, assuming one, two, and four frames? Remember that all frames are initially empty, so your first unique pages will cost one fault each. a. LRU replacement b. FIFO replacement c. Optimal replacement